The API (and implementation) in canonical.cachedproperty has been getting a bit hairy in order to support the cache invalidation work that Rob has been doing.
I've had a idea rattling around for a while to make a nicer cached property API, so I started an experiment... and it turned out well, I think. Henning has reviewed it favourably - http://tinyurl.com/385e6r7 - but he asked that I get some feedback before it lands (or to prevent it from landing). Some key points: - Cached properties are declared using a cachedproperty decorator, so most code will not require any modification. - This first branch allows both canonical.cachedproperty and lp.services.propertycache to co-exist. A subsequent branch will deprecate or remove canonical.cachedproperty. - The cached values are stored in a separate cache object, obtained by adapting the target object to IPropertyCache: >>> cache_for_model_object = IPropertyCache(model_object) >>> cache_for_model_object.a_cached_property = 1234 It behaves mostly like a regular instance, but has three extra features for convenience: * The cache can be iterated over to get the names of currently cached values. >>> list(cache_for_model_object) ['a_cached_property'] * The cache responds to membership tests. >>> 'a_cached_property' in cache_for_model_object True * If something is not found in the cache, deleting it is a no-op rather than an error. >>> del cache_for_model_object.a_cached_property >>> del cache_for_model_object.a_cached_property - The cache can be cleared using an IPropertyCacheManager: >>> IPropertyCacheManager(cache_for_model_object).clear() or, more simply: >>> IPropertyCacheManager(model_object).clear() That's about it. It's pretty simple and unsurprising to use. See lib/lp/services/doc/propertycache.txt for the full documentation. Gavin. _______________________________________________ Mailing list: https://launchpad.net/~launchpad-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~launchpad-dev More help : https://help.launchpad.net/ListHelp
